Levofloxacin is not usually the first choice for a simple upper respiratory tract infection, because most cases are viral and improve without antibiotics. When it is prescribed for confirmed or strongly suspected bacterial infections, the commonly used adult dose is 500 mg once daily, and in some moderate to severe cases, doctors may use 750 mg once daily depending on the infection and clinical condition. The duration is generally around 5 to 14 days, depending on how severe the infection is and how the patient responds, rather than a fixed number for everyone. It is important to understand that antibiotics like levofloxacin should only be used when a doctor feels they are necessary, because wrong use can lead to side effects and antibiotic resistance. If symptoms are mild or recent, supportive care like rest, warm fluids, steam inhalation, and hydration is often enough, as many upper respiratory infections are viral. If fever is persistent, breathing difficulty develops, chest pain appears, or symptoms are not improving after a few days, a medical review is needed to reassess whether an antibiotic is actually required or a different diagnosis is present.